Make lemming dataplane gnmi use the SAI API

[DanG100]

sorry about the size of this, it was smallest i could do get to the tests passing

• summary of changes: simplified the dpb.Route message and changed sysrib to use it
• modified the reconcilers package to call the sai API.

still a little more work to remove engine entirely and change the directory structure a bit

[github-actions]

Pull Request Test Coverage Report for Build 7053217846

• 112 of 974 (11.5%) changed or added relevant lines in 15 files are covered.
• 90 unchanged lines in 6 files lost coverage.
• Overall coverage decreased (-0.002%) to 2.431%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
dataplane/standalone/saiserver/saiserver.go	0	1	0.0%
dataplane/forwarding/protocol/metadata/metadata.go	0	2	0.0%
dataplane/standalone/saiserver/switch.go	18	20	90.0%
dataplane/standalone/saiserver/acl.go	6	9	66.67%
dataplane/internal/engine/engine.go	0	4	0.0%
dataplane/reconcilers_linux.go	0	7	0.0%
dataplane/internal/kernel/kernel.go	0	8	0.0%
dataplane/standalone/saiserver/hostif.go	22	30	73.33%
dataplane/standalone/saiserver/routing.go	4	37	10.81%
dataplane/server.go	0	44	0.0%

Files with Coverage Reduction	New Missed Lines	%
dataplane/internal/engine/engine.go	1	0.0%
dataplane/reconcilers_linux.go	1	0.0%
dataplane/standalone/saiserver/acl.go	1	64.35%
dataplane/standalone/saiserver/routing.go	2	70.62%
gnmi/oc/structs-3.go	40	0.05%
bgp/gobgp.go	45	41.58%

Totals
Change from base Build 6897489228:	-0.002%
Covered Lines:	15769
Relevant Lines:	648772

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💛 - Coveralls

[DanG100]

i haven't seen any flakiness with the tests now.